Scavenge system for engines



. NOV. 5, 1946. A. KALrr|NsKY 2,410,448

SCAVENGE SYSTEM FOR ENGINES Filed May l1, 1945 2 Sheets-Sheet`l i l'u'/.........................7;

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INVENTOR @www Patented Nov. 5, 1946 SCAVEN GE SYSTEM FOR ENGINES Andrew Kalitinsky, Eagleville, Conn., assignor to vUnited Aircraft Corporation, East Hartford, Conn., a corporation of Delaware Application May 11, 1943, Serial No. 486,611

(Cl. 12B-51) 16 Claims.

The present invention relates to an air scavenging system lor an opposed piston engine and is especially adapted for a free-piston engineand-compressor unit.

In conventional opposed piston engines the scavenge ports are at one end of the engine cylinder and the exhaust ports at the opposite end. When the ports are uncovered by the pistons, the cool scavenging air enters one end of the cylinder and pushes the burned gases out of the exhaust ports at the other end. The cool air passes over, and cools, the head of the piston adjacent the scavenge ports, but the other piston is continuously subjected only to the high temperatures of the burned gases. An object of this invention is to provide for directing cool scavenge air onto the heads of both pistons.

This object is accomplished by providing scavenge ports at both ends of the engine cylinder so that the scavenging air enters the cylinder over the heads of both pistons. For efficient removal of the burned gases, however, the general flow of the gases should be in one direction from one end to the other of the engine cylinder. One feature of the invention provides for maintaining a general one-direction iiow of gases within the engine cylinder even though scavenging gases are admitted at both"`ends of the cylinder. For this purpose the scavengeport area at one end of the 'cylinder is greater than at the other, and an vexhaust port is provided adjacent the end `of the cylinder which has the smaller, scavenge port area.

Other objects and advantages will be apparent from the specification and claims, and from the accompanying drawingswhich illustrate what is now considered to be a preferred embodiment of the invention.

Fig. 1 is a sectional View through the engineand-compressor unit.

Fig. 2 is an enlarged sectional View of the engine cylinder. k

Fig. 3 is'a fragmentarysectional view of one of the air valves. Y

The unit shown includes an engine cylinder lllAhaving reciprocating pistons I2 and I4 t0 which compressor pistons I6 and i8 in cylinders 26 and 22 are integrally connected. VSleeves 24 and 26 attached to the compressor pistons complete the reciprocating piston assemblies. The sleeves in combination with stationary lpistons 28 and 36 form air spring cylinders.

The piston assemblies are moved apart by the burning of -fuel injected into engine cylinder I6 by one or more devices 32. Air compressed in the air spring cylinders on the power stroke returns the piston assemblies. The assemblies are always maintained at equal distances from the center of the engine by a linkage which may include the racks 34 on the compressor pistons meshing with a pinion 36.

Intake manifold 38 conducts air to intake valves l0 through which air alternately enters opposite ends of the compressor cylinders. The vcompressed air leaves the cylinder through discharge valves 42, also at opposite ends of the compressor cylinders, and passes through scavenge manifold 4t through ports 46 and 48 which are uncovered by pistons l2 and i4 at the end of the power stroke, thereby permitting air to be blown through the engine cylinder and exhaust ports 56 and 52 into exhaust manifold 54. Valves 46 and 42 may be the type shown in the Huff Patent No. 1,599,414, dated September 14, 1926, in which, as shown in Fig. 3, each valve includes spring pressed valve blades 49 engaging seats 5|.

The engine scavenge ports 46 and 46 are spaced apart in a position to be uncovered by the engine pistons at the outer ends of their stroke. The exhaust ports 56 and 52 are also spaced apart and adjacent the scavenge ports. Each scavenge port i6 or 48 consists of a number of openings in the engine cylinder, as seen more particularly in Fig. 2, and the total area of the openings forming port 46 is considerably larger than the total area of the openings forming port 48. With the'scavenge ports communicating with the scavenge manifold 44 and located adjacent the heads of the opposed pistons when they are at the outer ends of their strokes, the cool scavenge air passes over the heads of both pistons as soon as the ports are uncovered.

Each exhaust port 5U or 52 comprises a number of openings and the total area of the openings forming port 52 is considerably greater than the area of the openings forming port 56. Thus the exhaust ports, which are adjacent and be'- tween the scavenge ports, are so arranged that thelarger exhaust port is at the end of the engine cylinder opposite to the larger scavenge port. Both exhaust ports 56 and 52 are connected to the manifold 54 through which all the compressed gases are discharged to do useful work.

During'the strokes of the pistons in both directions, air in the compressor cylinders is delivered under pressure to scavenge manifold ifi to provide for the desired scavenge action when pistons uncover the scavenge ports 46 and 48 during their outward stroke.

When the pistons reach the outer end of their normal strokes (the position shown in Fig. 2), all of the ports are uncovered and cool scavenging air Yenters at both ends of the cylinder over the heads of the opposed pistons. A relatively large proportion of the scavenge air entering the larger scavenge port 46 establishes substantially a one-direction iiow of gases axially of the en. gine cylinder, the gases discharging primarily throughthe larger exhaust `port 52.. .Scavenge air entering port 48 serves to aid in cooling the head of piston I4 before exhausting through port 52.

It is to be understood Vthat the invention is not limited to the specic embodiment herein illustrated and described, but may be used in other ways without departure from its spirit ,as dened by the following claims.

I claim:

l. In an engine, a cylinder .with opposed pistons reciprocating therein, said cylinder having-spaced intake ports adapted to be uncovered by the pistons during their reciprocation, and an exhaust port between said intake ports, one intake port being larger than the other.

2. In an engine, a cylinder with `.opposed pis-` tons reciprocating therein, said cylinder lhaving spaced intake ports adapted to be uncovered by the pistons during their-reciprocation andan exhaust port adjacent each intake port, said exhaust ports being located between the intake ports, one intake port being `larger than the other.

3. In an engine, a cylinder with opposed pistons movable therein, said cylinder having ,axially spaced intake ports and an exhaust port adjacent each intake port, one exhaust `port being larger than the other.

4. Inv an engine, a cylinder with opposed pistons movable therein, said cylinder having axially spaced intake vports and an exhaust port adjacent each intake port, one intake port being larger than the other.

5. In an engine, a cylinder withopposed pistons movable therein, said cylinder having axially spaced intake ports and an exhaust port adjacent each intake port, one exhaust fport being larger than the other, and the intake port adjacent the larger exhaust port being smaller than the .other intake port.

6. In an engine, a cylinder with opposed pistons reciprocating therein, said cylinder having axially spaced exhaust ports adapted to fbe lmcovered by the pistonsduring their reciprocation and an intake port-adjacenteach exhaust port, said exhaust ports being located between the intake ports, one exhaust port Vbeing 'larger than the other. i

7. In an engine, a cylinder `wi-tli opposed Ypistons reciprocating therein, said cylinder having axially spaced exhaust .ports adapted Yto be Auncovered by the pistons during their ,-reciprocation` and an intake Vport adjacent nach ,exhaust sport, said exhaust ports being located betweenzthe intake ports, :one intake portibeing larger than -the other.

8. In an engine, a cylinder, vopposed,ipistons movable alternately `toward and :away from each other in said cylinder, Vsaid rcylinder ,havingscaivenge and exhaust pQrtS adjacent :One end .of the cylinder to be uncovered byoneof the pistons vin its outwardmovement, `the, ,other end or the cylinder having atleast one scavenge port :toibe un-" covered .by the other lpiston `during `its outwar-d movement, the scavenge'port adjacent the `exhaust port being smaller thanrthe;other-,scavenge port.

`9. In an engine, a fcylinder, opposed pistons movable alternately toward and away from veach other in said cylinder, said cylinder havingscav enge -andexhaust ports-adjacent one end of the cylinder to be uncovered by one of the'pistons in its outward movement, the other end Aof the cylinder having a scavenge port adapted `tao-be uncovered by 'said` other .piston 'during :its outward movement, ithje .scavenge port at one -endf being larger than the scavenge port at the other end.

10. In an engine, a cylinder, opposed pistons movable alternately toward and away from each other in said cylinder, said cylinder having scav- `enge and exhaust ports adjacent one end of the cylinder to be uncovered by one of the pistons in its outward movement, the other end of the cylinder having a scavenge port adapted to be jacent opposite ends thereof to be uncovered -by the `opposed pistons as they reach the outer ends of their strokes, each set including at least one row of ports extending circumferentially of the cylinder. .if

12. In a scavenging system, an engine cylinder, opposed pistons reciprocating in said `cylinder, sets of scavenge ports in said cylinder adjacent opposite ends thereof to be uncovered by the opposed pistons as they reach the outer ends of their strokes, and at least one set of exhaust ports in said cylinder between said scavenge ports and adjacent one set of said scavenge ports.

13. In a scavenging system, an engine cylinder, opposed pistons reciprocating in said cylinder, sets of scavenge ports in said cylinder adiacent opposite ends thereof to be uncovered by the opposed pistons as they reach the outerends of their strokes, and sets of exhaust 4 ports between said scavenge ports, there being one set of exhaustv ports adjacent each end vof the cylinder.

14.. In a scavenging system, an engine cylinder, opposed pistons reciprocating in said cylinder, scavenge ports adjacent .opposite ends ofsaid cylinder to be uncovered `by the opposed pistons as they reach the outer ends of their strokes, and at least one exhaust port between the scavenge ports and `adjacent the rscavenge port at one end of the cylinder, the scavenge port to .which .the exhaust port is adjacent being smaller kin arca than the scavenge port adjacent the oppositevend of the cylinder.

l5. In a free-piston engine and compressor, an engine cylinder, opposed pistons reciprocating therein, at least one compressor cylinder, ra cornpressor piston in said compressor cylinder and movable with one of the pistonsl in the engine cylinder, scavenge ports adjacent opposite ends of the engine cylinder to be uncovered by the pistons as they reach the outer ends ,of their strokes, and a manifold connecting the Acompressor cylinder to said scavenge vports for delivery of compressed gases to said engine cylinder adjacent oppcsite ends thereof and in front of bothV pistons.

16. 'In `a freer-piston engine and compressor, an engine cylinder, opposed pistons reciprocating therein, at leastonecompressor cylinder, a compressor piston in said compressor cylinder and movable with one lof the `pistons in the engine cylinder, Yscavenge `ports adjacent opposite ends of the engine cylindertobe uncovered by `thepistons as they reach the outer ends Vof their strokes, a manifoldconnecting the compressor cylinderto said scavenge ports for delivering compressed gases to said engine cylinder adjacent .opposite ends --thereof and in front of the pistons therein, and exhaust-ports in said engine cylinder.

ANDREW KALrTrNsKY. 

